This invention relates to an improved piezoelectric motor for use in dither drives for ring laser gyroscopes. More particularly, this invention relates to improvements in the motor and in the piezoelectric transducers used as actuators in such motors.
Piezoelectric motors have been used in the past for the purpose of dithering ring laser gyroscopes. In one such motor, one or more piezoelectric transducers are fastened to flexible spokes connecting the outer movable rim of the gyroscope to an inner, fixed hub. The transducers are driven by a suitable AC voltage and bend together, moving the outer rim back and forth in an oscillatory motion. In this known structure, the transducers are attached to a heavily stressed region near the hub of the spoke by means of an adhesive which is subject to failure, during operation of the motor, because of the high stress. Also, because of the high stress, very thin piezoelectric elements must be used in the transducers, making the motor structure expensive.
A second drawback in this design is the fact that one side of the transducer is necessarily grounded to the spoke to which it is attached. The transducer drive currents, passing through to ground, cause error voltages to appear in other circuits which use the same ground. In some cases, this problem may be so severe as to necessitate the use of an isolation transformer for driving the motor. Such an isolation transformer is heavy and is particularly undesirable when the ring laser gyroscope is to be used in air-borne navigation equipment.
It is an object of the present invention to provide a piezoelectric motor for driving ring laser gyroscopes which is free of the above disadvantages.